High speed rotary hydraulic motor



Jan. 14, 1969 E. l.. ACILEY l HIGH SPEED ROTARY HYDRAULIC MoToR original Filed Feb. 26,1965

Edv-VG d Lgckley INVENTORL United States Patent O 3,421,412 HIGH SPEED ROTARY HYDRAULIC MOTOR Edward L. Ackley, 1916 SE. 50th, Portland, Oreg. 97215 Original application Feb. 26, 1965, Ser. No. 435,471, now

Patent No. 3,350,985, dated Nov. 7, 1967. Divided and this application Sept. 15, 1967, Ser. No. 668,032 U.S. Cl. 91-87 2 Claims Int. Cl. F01c 1/18; F16j 15/54; F16c 33/78 ABSTRACT OF THE DISCLOSURE A cylindrical case houses recessed front, rear and central core segments supporting a drive shaft. One of a pair of gears in the central segment is secured to the drive shaft, and hydraulic fluid under pressure is conveyed to and from the gears through passageways in the front segment and conduits in a handle connected to the case. Bearings and seals are associated with the segments and drive shaft, and the outer end of the latter supports a rotary tool.

This application is a division of my application Ser. No. 435,471, filed Feb. 26, 1965 and now Patent No. 3,350,- 985.

This invention relates to high speed rotary hydraulic motors.

Although various types of rotary hylraulic motors are well-known, need exists for an improved motor of this class which may be applied satisfactorily to heavy duty uses such as the operation of high speed rotary pruning saws.

It accordingly is the general purpose of the present invention to provide a heavy duty, high speed, hydraulic motor:

(1) which operates at exceptionally high speed, for example at speeds of in excess of 15,000 r.p.m.;

(2) which does not heat excessively, even when operated at high speed;

(3) which is sealed effectively against leakage of high pressure hydraulic fluid;

(4) which is protected against heavy thrust stresses such as might be caused by operating a rotary saw afxed directly to the drive shaft of the motor;

(5) which does not vibrate excessively at high speeds;

(6) which may be disassembled and assembled easily for servicing and repair;

(7) which is versatile, being suitable for use in a diversity of applications;

(8) which has a long service life.

In the drawings:

FIG. 1 is a longitudinal sectional View of the rotary hydraulic motor of my invention;

FIGS. 2 and 3 are front and back elevations of the motor, respectively, FIG. 2 being partly insection;

FIG. 4 is a fragmentary, detail sectional view taken along line 4-4 of FIG. 3 and illustrating the manner of assembling the motor;

FIG. 5 is a fragmentary, sectional View taken along line 5-5 of FIG. 1 and illustrating a novel gear drive which may be employed in the motor; and

FIG. 6 is an enlarged fragmentary view illustrating seal means employed in the motors of my invention to seal the motor against leakage of high pressure hydraulic fluid.

The motor of my invention is illustrated in the drawings 3,421,412 Patented Jan. 14, 1969 in its application to a rotary pruning saw although it is applicable also to many other uses. As shown particularly in FIGS. l, 2 and 3, the saw is housed in a case 10 comprising a short, hollow cylinder open on both ends and made of stout metal.

The case is provided with a connector 12 comprising a short pipe which extends at right angles to the case communicating with the interior thereof. It telescopes over a hollow handle 14 which in a pruning saw application may be twelve or fteen feet long.

The handle, in turn, houses hydraulic fluid conduits 16, 18, the one being for the transmission of input uid under pressure and the other for the transmission of exhaust uid. These may be included in an hydraulic circuit designed to provide hydraulic uid under pressure to the motor as required for its operation.

Case 10 houses a transversely segmental core which in the illustrated form of the invention includes three longitudinally recessed segments: a rear segment 20, a central segment 22, and a front segment 24.

Front segment 24 is formed With first connecting passageways 26, 28 and second connecting passageways 30, 32 which communicate, respectively, with input and exhaust conduits 16, 18 `by means of which hydraulic fluid is supplied to and exhausted from the driving elements of the motor.

A seal ring 34 and a seal ring 36 are associated, respectively, with passageways 26 and 30 to prevent the escape of iiuid.

Securing means are provided for securing the core segments to each other and for securing the assembled core in the case. It is a particular feature of the invention that the securing means used permit easy disassembly and assembly of the motor as required for its servicing and repair.

To achieve this purpose, there are provided a plurality of cap screws 40 which penetrate segments 20 and 22 and which are threaded into front segment 24, being arranged longitudinally of the case. In addition, there are provided one or more screws 42 which extend radially of the case, penetrating the case and being: threaded into or seated in the side of one of the core segments, for example central core segment 22 as shown in FIG. 1.

To assist in matching up the core segments when assembling them, there are provided a pair of locating pins 44 which are insertable in registering apertures in the segments when the segments are arranged in proper relation for coupling them by means of screws 40, 42.

The recess in central core segment 22 provides a chamber 48, FIG. 5. This chamber is sealed olf by means of seal rings 50, 52.

Meshing hydraulic gears 54, 56 work in chamber 48. As will be noted from FIG. 5, the teeth of these gears are unique in that they extend radially from the gear base and are tapered uniformly toward an outer terminal apex. At no place in their contour are the gear teeth undercut.

As a result, they mesh smoothly without trapping oil during any phase of their operation. This in turn assists in keeping the heat generated by operation of the motor at a minimum. It also assists in reducing the operation vibration.

Hydraulic gear 54 is keyed to a shaft 58, the ends of which are journaled in needle bearings 59.

Hydraulic gear 56 is keyed or otherwise fixed to the drive shaft of the motor, indicated generally at 60. Shaft 60 is free to move longitudinally within limits thereby avoiding applying a thrust force against the gear, with consequent development of heat.

Shaft 60 is elongated, extending completely through case in an axial direction. It is stepped in its longitudinal configuration being provided with an inner section 62 of relatively restricted diameter and an outer section 64 of relatively substantially enlarged diameter, the two sections being separated by an annular shoulder 66.

Inner section 62 of shaft 60 mounts gear 56. it is journaled in suitable bearings such as needle bearings 68 positioned one on each side 'of the gear.

As is apparent in FIG. 1, the outer end of outer enlarged section 64 of drive shaft 60 extends completely beyond the plane of case 10 and mounts the appliance to be driven by the motor. Thus the outer end of the shaft may be threaded and may mount a saw blade 70 between clamps 72. Nut 74 threaded on the end of the shaft supplies ihe clamping pressure required releasably to mount the saw blade.

It is a particular feature of the invention that shaft 60 is supported in bearing means which braces the shaft against thrust in both directions, as well as against radial Stresses, thereby relieving Wearing strain which otherwise would be exerted on the motor gears and also reducing the tendency of the motor to develop heat at high operating speeds. To this end there is provided a husky bearing 80 which may comprise an assembly of one or more ball or roller bearings arranged end to end with the inner end of the bearing abutting against shoulder 66 of the shaft.

Retaining means are provided for retaining bearing 80 in place while at the same time resisting shaft thrust in both directions.

The retaining means include a first snap ring 82 seated in the recess in front core segment 24 and bearing against the outer margin of bearing 80. This ring takes the thrust of the drive shaft when the thrust is exerted outwardly, or to the right as viewed in FIG. 1.

Seated on the outer end of enlarged section 64 of shaft 60 is a second retaining ring 84. This also is adjacent the outer end of bearing 80. It takes the thrust of the drive shaft when the thrust is exerted inwarly, i.e. toward the left as viewed in FIG. 1.

It thus Will be noted that bearing 80, which journals the enlarged section of the drive shaft, takes the major portion of the working stresses occurring during operation of the motor, whether the stresses occur radially or endwise. This in turn saves stress and wear on the relatively sensitive gears of the motor.

Another particular feature of the invention is the provision of novel seal means along the drive shaft for preventing the escape of high pressure hydraulic uid from the gear chamber. The construction of the seal means is shown in FIGS. 1 and 6.

A seal retainer 90 is seated in the longitudinal recess in core segment 24, being arranged coaxially with the inner restricted section 62 of the drive shaft 60. It is located inside of shoulder 66 and is retained in place by means of a snap ring 92 seated in core segment 24. The outer peripheral surface of seal retainer 90 is recessed to accommodate a static seal O-ring 94.

Retainer 90 houses a seal member 96 which likewise is coaxial with section 62 of shaft 60 against which it bears. Its outer peripheral surface is recessed to accommodate a static seal O-ring 98. Its inner peripheral surface is recessed to accommodate a quad-ring 100.

The materials of which the sealing elements are composed is of importance in determining the efficiency and service life of the seal. It is one of the objects of my invention to fabricate shaft section 62, seal 96 and quadring 100 of relative materials having friction characteristics such that the friction coefficient of quad-ring 100 with reference to shaft section 62 will be greater than the friction coefiicient of the quadering with reference to seal 96.

For example, where shaft section 62 is of metal, quadring 100 of rubber and seal 96 of molybdenum sulfidelubricated nylon, the frictional coefficient of the rubber quad-ring with reference to the metal shaft section will be greater than its frictional coefiicient with respect to the lubricated nylon seal ring.

As a consequence, during high speed operation of the motor, quad-ring 100 will rotate within the recess in which it is housed to an extent suficient to relieve the stress and prevent slippage of O-ring 98, thus preserving the static seal afforded by the latter ring. This feature not only improves the seal but also lengthens the service life of the sealing member substantially.

It thus will be seen that the construction of the motor herein described is Such as to achieve the various objects of the invention.

The motor may be assembled and disassembled rapidly and easily simply by inserting or removing screws 40 and 42. During high speed operation of the motor the pointed teeth of gears S4, S6 mesh cleanly without trapping oil, thereby reducing friction and heat generation.

Large bearing on the enlarged portion of stepped shaft 60 takes the major portion of the developed stress during heavy duty service, including both the radial stress and the thrust stress in both directions. Wear on gears 54, 56 as well as on bearings 59, 68 thus is minimized.

In addition, the efficiency of the hydraulic fiuid seal is greatly improved first, by locating it on section 62 of the drive shaft which has a peripheral speed substantially less than that of enlarged section 64, and secondly by providing the special inner seal arrangement illustrated in FIG. 6 above described which prevents Wear of the sealing elements.

The motor accordingly is characterized by a long and efficient service life even when applied to the operation of high speed, heavy duty equipment such as rotary pruning saws.

It is to be understood that the form of my invention herein shown and described is to be taken as preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a high speed rotary hydraulic gear motor having a pair of meshing, journaled drive gears, a sealed drive shaft assembly comprising (a) a stepped drive shaft having an outer end of enlarged diameter and an inner end of restricted diameter,

(b) the inner end mounting one of the drive gears,

(c) bearing means journaling the enlarged outer end of the shaft, and

(d) hydraulic fluid seal means associated with the restricted inner end of the shaft, the seal means comprising (l) a recessed seal retainer on a restricted inner end of the shaft,

(2) a seal member seated in the recess in sealing relation with the drive shaft,

(3) the inner side of the seal member being provided with an inner seal ring engaging the drive shaft, and v (4) the outer side of the seal member being provided with an outer seal ring engaging the seal retainer,

(5) the shaft, seal member and inner seal ring being of different types of material wherein the coefficient of friction of the inner seal ring with respect to the shaft is greater than its coefficient of friction with respect to the seal member during operation of the motor, whereby to afford rotation of the inner seal ring with the drive shaft and relative to the seal member to inhibit rotation of the outer seal ring.

inner seal ring is rubber.

References Cited UNITED STATES PATENTS Altmann et al 30S-36.1 Larson 103--126 X Hoffer 103-126 Wood 277-95 Aschinger 277-95 Hanley 30S-36.1 Lee et al 277-95 X Johnson 103--126` X Lauck 103-126 Miller BOS-36.1 Ackley `9l87 U.S. C1. X.R. 

